1. Field of the Invention
This invention relates to transport truck trailers and more particularly to a slidable mounting assembly for the rear wheels thereof.
Relatively large size transport truck trailers are customarily provided with a rear wheel and axle subframe supported by the trailer rear wheels with the subframe longitudinally underlying the trailer bed rails in supporting relation. The rear wheel subframe is longitudinally slidable relative to the trailer bed rails and is normally secured thereto by locking pins projecting horizontally through cooperating aligned transverse openings formed in the rear wheel subframe and trailer bed supporting rails.
In practice, the rear wheel subframe is moved relative to the trailer to equalize or distribute the load on the trailer relative to the trailer wheels and truck tractor wheels. In order to reposition the trailer wheels, either forwardly or rearwardly, relative to the trailer bed, the locking pins are temporarily withdrawn and the trailer is backed for contact of the trailer rear wheel assembly with a solid object below the level of the trailer bed. Alternatively, the trailer is forced in a rearward direction by the truck tractor which moves the trailer bed relative to the rear wheel subframe. In the event the rear wheels must be moved rearwardly relative to the trailer bed, the rear wheel brakes are usually "set" so that the wheels remain stationary relative to their position on a supporting surface while the truck tractor moves the trailer bed forwardly relative to the position of the rear wheels. However, this common practice of repositioning the wheels relative to the trailer is not entirely satisfactory. The repeated bumping and banging of the trailer components lead to damage to the trailer, its undercarriage or components of the load carried thereby. Further, such sliding action of the rear wheels relative to the trailer is a time consuming operation particularly when attempting to align the position of the locking pin receiving holes to secure the rear wheels in the new position relative to the trailer. Thus, it seems readily apparent that there is a need for an apparatus and system for more easily and quickly facilitating the repositioning of the trailer supporting wheels relative to the trailer unit.
2. Description of the Prior Art
I do not know of any patent that is particularly pertinent to this invention.
Prior art generally relates to apparatus as described in the above background section wherein the wheels/axle subframe remains in frictional sliding contact with the relatively moveable supporting elements during the forward or rearward movement of the removable portion relative to the trailer bed. Obviously, the coefficient of sliding friction between the moveable elements relative to the stationary elements is a function of the mass, area in contact and the condition of the surfaces involved.
Most prior patents relate to earth supported tracks having chocks thereon for retarding movement of the trailer rear wheels in a forward or rearward direction while adjusting their position relative to the trailer or to electrical or electronic sensing means enabling the driver to withdraw and reinsert the slider locking pins during the rear wheel adjustment action.
Of interest are the U.S. Pats. to Massey U.S. Pat. No. 3,963,259 and Landoll U.S. Pat. No. 4,125,198.
To achieve the rear wheel sliding action relative to the trailer Massey mounts the trailer bed on trailer wheel subframe supported V-pulleys which obviously reduces the coefficient of sliding friction of the trailer undercarriage relative to the trailer bed.
The Landoll patent similarly mounts rollers on his undercarriage engaged by inclined surfaces on his trailer bed support rails which permit rearward longitudinal movement of the trailer bed relative to its undercarriage for a rearward downwardly inclined position of the trailer bed for loading and unloading the trailer.
This invention is distinctive over both of the above patents and other prior art by providing a series of ramp climbing rollers mounted in his rear wheel subframe which move upwardly and temporarily lift the trailer bed overlying portion relative to the wheel subframe in a frictional reducing action permitting the trailer bed to be easily moved in either a forward or rearward direction. After adjusting the position of the trailer subframe the rollers therein are retracted to an out-of-contact position relative to the trailer bed rails.